I like the head, but the body and shoes need work in my opinion. I'm glad this isn't one of those cruddy recolors sent in by Fanboys. I suggest looking at the sprites of Sonic, Tails, and Knuckles, and try shaping A-Star's body to look like theirs. Also, considering he's a hedgehog, he most likely needs spines on his back, and a tail should also be added. Another thing: His head makes it look like he's looking up. Is he suppose to look like that? In any case, I would like to see how this turns out in the future. :)
P.S. His hands look like balls. I'm pretty sure they should not really look like that in the Sonic Universe. Try making them look more like gloves or mittens. Also, try looking at the sprites of Sonic, Tails, and Knuckles and try to make it that his shoes look more like them. Those shoes barely look like shoes, trust me.